Vulnerability-Lookup

GHSA-37CH-88JC-XWX2

Vulnerability from github – Published: 2026-03-27 20:04 – Updated: 2026-03-27 20:04

Summary

path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters

Details

Impact

A bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b-:c or /:a-:b-:c-:d. The backtrack protection added in path-to-regexp@0.1.12 only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, so capture groups overlap and cause catastrophic backtracking.

Patches

Upgrade to path-to-regexp@0.1.13

Custom regex patterns in route definitions (e.g., /:a-:b([^-/]+)-:c([^-/]+)) are not affected because they override the default capture group.

Workarounds

All versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b-:c to /:a-:b([^-/]+)-:c([^-/]+).

If paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length.

References

Severity ?

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "path-to-regexp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.1.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-4867"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1333"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-27T20:04:53Z",
    "nvd_published_at": "2026-03-26T17:16:42Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nA bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is not a period (`.`). For example, `/:a-:b-:c` or `/:a-:b-:c-:d`. The backtrack protection added in `path-to-regexp@0.1.12` only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, so capture groups overlap and cause catastrophic backtracking.\n\n### Patches\n\nUpgrade to [path-to-regexp@0.1.13](https://github.com/pillarjs/path-to-regexp/releases/tag/v.0.1.13)\n\nCustom regex patterns in route definitions (e.g., `/:a-:b([^-/]+)-:c([^-/]+)`) are not affected because they override the default capture group.\n\n### Workarounds\n\nAll versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change `/:a-:b-:c` to `/:a-:b([^-/]+)-:c([^-/]+)`.\n\nIf paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length.\n\n### References\n\n- [GHSA-9wv6-86v2-598j](https://github.com/advisories/GHSA-9wv6-86v2-598j)\n- [Detailed blog post: ReDoS the web](https://blakeembrey.com/posts/2024-09-web-redos/)",
  "id": "GHSA-37ch-88jc-xwx2",
  "modified": "2026-03-27T20:04:53Z",
  "published": "2026-03-27T20:04:53Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pillarjs/path-to-regexp/security/advisories/GHSA-37ch-88jc-xwx2"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-4867"
    },
    {
      "type": "WEB",
      "url": "https://blakeembrey.com/posts/2024-09-web-redos"
    },
    {
      "type": "WEB",
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-9wv6-86v2-598j"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pillarjs/path-to-regexp"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pillarjs/path-to-regexp/releases/tag/v.0.1.13"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters"
}

CVE-2026-4867 (GCVE-0-2026-4867)

Vulnerability from cvelistv5 – Published: 2026-03-26 16:16 – Updated: 2026-03-26 16:52

Title

path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters

Summary

Impact: A bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b-:c or /:a-:b-:c-:d. The backtrack protection added in path-to-regexp@0.1.12 only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, so capture groups overlap and cause catastrophic backtracking. Patches: Upgrade to path-to-regexp@0.1.13 Custom regex patterns in route definitions (e.g., /:a-:b([^-/]+)-:c([^-/]+)) are not affected because they override the default capture group. Workarounds: All versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b-:c to /:a-:b([^-/]+)-:c([^-/]+). If paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length.

Severity ?

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE

CWE-1333 - Inefficient Regular Expression Complexity

Assigner

openjs

References

URL

Tags

	https://github.com/advisories/GHSA-9wv6-86v2-598j
	https://blakeembrey.com/posts/2024-09-web-redos
	https://cna.openjsf.org/security-advisories.html

Impacted products

	Vendor	Product	Version
	path-to-regexp	path-to-regexp	Affected: 0 , < 0.1.13 (semver)

Credits

EthanKim88 blakeembrey UlisesGascon

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-4867",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-26T16:52:08.810671Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-26T16:52:14.893Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:npm/path-to-regexp",
          "product": "path-to-regexp",
          "vendor": "path-to-regexp",
          "versions": [
            {
              "lessThan": "0.1.13",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "EthanKim88"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "blakeembrey"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "UlisesGascon"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "Impact:\n\nA bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b-:c or /:a-:b-:c-:d. The backtrack protection added in path-to-regexp@0.1.12 only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, so capture groups overlap and cause catastrophic backtracking.\n\nPatches:\n\nUpgrade to path-to-regexp@0.1.13\n\nCustom regex patterns in route definitions (e.g., /:a-:b([^-/]+)-:c([^-/]+)) are not affected because they override the default capture group.\n\nWorkarounds:\n\nAll versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b-:c to /:a-:b([^-/]+)-:c([^-/]+).\n\nIf paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length."
            }
          ],
          "value": "Impact:\n\nA bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b-:c or /:a-:b-:c-:d. The backtrack protection added in path-to-regexp@0.1.12 only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, so capture groups overlap and cause catastrophic backtracking.\n\nPatches:\n\nUpgrade to path-to-regexp@0.1.13\n\nCustom regex patterns in route definitions (e.g., /:a-:b([^-/]+)-:c([^-/]+)) are not affected because they override the default capture group.\n\nWorkarounds:\n\nAll versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b-:c to /:a-:b([^-/]+)-:c([^-/]+).\n\nIf paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-1333",
              "description": "CWE-1333: Inefficient Regular Expression Complexity",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-26T16:16:25.501Z",
        "orgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
        "shortName": "openjs"
      },
      "references": [
        {
          "url": "https://github.com/advisories/GHSA-9wv6-86v2-598j"
        },
        {
          "url": "https://blakeembrey.com/posts/2024-09-web-redos"
        },
        {
          "url": "https://cna.openjsf.org/security-advisories.html"
        }
      ],
      "title": "path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters",
      "x_generator": {
        "engine": "cve-kit 1.0.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
    "assignerShortName": "openjs",
    "cveId": "CVE-2026-4867",
    "datePublished": "2026-03-26T16:16:25.501Z",
    "dateReserved": "2026-03-25T20:11:53.714Z",
    "dateUpdated": "2026-03-26T16:52:14.893Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-37CH-88JC-XWX2

Impact

Patches

Workarounds

References

CVE-2026-4867 (GCVE-0-2026-4867)

Tags

Sightings

Nomenclature